Abstract:

: The amendment of sandy Haplic Arenosol and clayey loam Gleyic Fluvisol with two rates of biochar derived from the slow pyrolysis of wood feedstock was evaluated under anaerobic conditions in a 63-day laboratory experiment. The rates of biochar were 15 and 30 t ha −1. Both rates of biochar were applied either with or without 90 kg ha −1 of nitrogen fertilizer (NH 4NO 3). Soils with no amendments were used as control treatments. Our results showed that only the incorporation of 15 t ha −1 of biochar, compared with the control treatment, led to a significant ( p < 0.05) increase in volumetric water content of the sandy soil and a significant ( p < 0.05) decrease in the parameters of the clayey loam soil. Increasing the biochar rate from 15 to 30 t ha −1 did not result in significant changes in volumetric water content in either type of soil. In the sandy soil, CO 2 emissions were significantly ( p < 0.05) higher in the treatments of 15 and 30 t ha −1 with N fertilizer compared with the control and N fertilizer treatment. In the clayey loam soil, the combined application of both rates of biochar with N fertilizer caused no significant increase in CO 2 emissions compared with the control and N fertilizer treatment. The incorporation of 30 t ha −1 of biochar into the sandy soil contributed to a significant ( p < 0.01) increase in the cumulative CO 2 flux compared with the control treatment. Application of 15 and 30 t ha −1 of biochar into the clayey loam soil led, respectively, to a significant ( p < 0.05) and a nonsignificant increase in the cumulative CO 2 fluxes compared with the control treatment.

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